The invention relates generally to power-driven conveyors and more particularly to modular plastic conveyor belts and modules and methods for splicing such belts together on a conveyor.
Modular plastic conveyor belts are constructed of a series of rows of one or more belt modules linked together end to end by hinge rods received in the interleaved hinge eyes of consecutive rows. One use for a modular plastic conveyor belt having a lot of open area for good air flow is as a cooling belt for rubber extrusions, such as tire tread and sidewall extrusions. Hinge rods made of polypropylene or acetal are commonly used in modular plastic belts and tend to wear out fairly quickly in abrasive environments, such as in a rubber-processing or tire plant's cooling line. Hinge rods made of certain nylon materials, such as nylon 6-6, have been shown to markedly increase rod life. As a consequence, nylon hinge rods are sometimes used in cooling belts. But, to hasten cooling, water is sprayed on the tire components as they are conveyed on the cooling belt. The nylon hinge rods absorb water, which causes them to grow in diameter and length. If the ends of the rods are not confined by the belt structure, the ends can grow past the outside edges of the belt and snag people or things alongside the conveyor. If the ends are confined by structure in the edges of the belt, the growing rods can push against and deform or break the edges of the belt. Sometimes the nylon hinge rods are cut short in order to accommodate the expected growth. In this case, the rods could be significantly short on wide belts, which would leave several links on the outside edge of the belt without rods. This leaves those links vulnerable to damage and reduces the effective pull strength of the belt. Thus, there is a need for a conveyor belt that can accommodate hinge-rod growth.
Another problem arises in the splicing of modular plastic conveyor belts in the field during initial installation or after repair. It is especially difficult to splice a belt together while simultaneously removing slack from the returnway—slack that is necessary to develop the back tension required in a low-tension belt conveyor. Typically, two hands are required to hold the ends of the belt together while interleaving the hinge eyes along the unconnected ends of the belt so that apertures through the interleaved hinge eyes are aligned to form a continuous passageway for a hinge rod, which must then be inserted in and pushed through the passageway by a third hand to splice the belt together. Thus, there is a need for easing the splicing of modular conveyor belts.